Fuel supply system, carburetor for use in the same and method

ABSTRACT

Fuel supply system for an internal combustion engine having at least one cylinder with a moving piston therein to provide a combustion chamber within the cylinder which is adapted to be placed in communication with an intake opening by operation of an intake valve. A carburetor and means for supplying fuel to the carburetor are provided as a part of the system. The carburetor includes means forming a wave tube of substantially constant cross-sectional area with one end open to the atmosphere and with the other end adapted to be placed in communication with the intake opening. Means forming an orifice is disposed in the wave tube for supplying fuel to the interior of the wave tube. Throttle means is disposed in the wave tube between the region in which the fuel is introduced and the intake opening. The means for supplying a liquid fuel to the carburetor includes means for supplying fuel to a level which approximately just covers the orifice.

United States Patent 1191 Beekhuis, Jr.

FOR USE IN THE SAME AND METHOD 608,2ll l/l935Germany...................... l23/l39 AV [76] Inventor: William H.Beekhuis, ,Ir., 27686 Natoma Rd., LOS Altos H1115, Calif. OTHERPUBLICATIONS 94022 Acoustic Vibrations, P. M. Morse et al., Journal of[22] Filed: May 13, 1974 Applied Phys1cs, Jan. 1938.

[21] Appl- N 469,474 Primary Examiner-Wendell E. Burns AssistantExaminer-D. Reynolds Related U.S. Application Data [63] Continuation ofSer. NO, 268,736, July 3, 1972, Attorney Agent firm-Flam Hohbach Testabandoned.

[57] ABSTRACT Cl 123/119 261/36 261/44 Fuel supply system for aninternal combustion engine 123/119 DB having at least one cylinder witha moving piston [i] I'll. Cl. [herein to provide a combustion chamberwithin the Field 123/1 19 l 19 139 cylinder which is adapted to beplaced in communical23/l39 52 52 261/36 44 R tion with an intake openingby operation of an intake valve. A carburetor and means for supplyingfuel to Raferences Cited the carburetor are provided as a part of thesystem. UNITED STATES PATENTS The carburetor includes means forming awave tube of 1,403,003 1/1922 Beatson 123/119 DB Substantially 1111mmcmss-secmnal area with 0118 1,633,928 6/1927 Donnelly 1 123/119 R endopen to the atmosphere and with the other end 2,059,417 11/1936 Thomas137/68 adapted to be placed in communication with the in- 2,827,0303/1958 Strumbos 123/139 take opening. Means forming an orifice isdisposed in 2,871,341 2/1959 Goodfidge et u 123/! 19 R the wave tube forsupplying fuel to the interior of the 2,894,497 7/1959 Bolles [23/52 Mwave tube Throttle means i disposed in the wave 2 3 g r tube between theregion in which the fuel is introzg 5 l I] o Z3 I duced and the intakeopening. The means for supply- 5,403 2/1969 May 123/]39 AW 3.5203847H970 Ruoff et aL 123/52 Mv mg a l quid fuel to the carburetor Includesmeans for 3,593,694 7/1971 Hilborn 123/119 R Supplying fuel to a levelWhlch PP Y Jllst 3,610,213 10/1971 Gianini 123/139 AW firs the Orifice-3,702,l22 ll/l972 Hanoaka 261/36 A 3,709,469 1/1973 Edmonston et al.261/44 R Clams 15 Draw 6 l 1 l8 l6 l8 41 if 5g I fi 1 1 32 23 Ill SHEETHTEHJUL 8 ms PME 1 FUEL SUPPLY SYSTEM, CARBURETOR FOR USE IN THE SAMEAND METHOD This is a continuation of application Ser. No. 268,736 filedJuly 3, 1972, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to fuel supplysystems, carburetor for use therein and a method for metering andatomizing liquid fuel for use with internal combustion engines.

Heretofore, many different types of fuel supply systems and carburetorshave been provided. However, such systems and carburetors for usetherein have suffered from a lack of wide operating ranges. In addition,such systems and carburetors have suffered from inadequate performanceoften caused gy inefficient atomization of the fuel and with undesirablepressure drops. There is. therefore, need for a new and improved fuelsupply system, carburetor for use therein and a method which overcomesthese disadvantages.

SUMMARY OF THE INVENTION AND OBJECTS The fuel supply system is for usewith an internal combustion engine having at least one cylinder with amoving piston therein to provide a combustion chamber within thecylinder which is adapted to be placed in communication with an intakeopening by operation of an intake valve. Means is provided which forms awave tube of substantially constant cross sectional area with one endopen to the atmosphere and with the other end adapted to be placed incommunication with the intake opening. Means forming an orifice isdisposed in the wave tube for supplying fuel to the interior of the wavetube. Fuel supply means supplies fuel at a level which covers theorifice. The cross-sectional area of the wave tube is sufficiently smallto permit shock wave metering and atomization of fuel supplied to thewave tube. Throttle means is disposed in the wave tube between theregion in which the fuel is introduced and the intake opening. Thethrottle valve is formed so that when it is in the fully open position,there is substantially no restriction to the airflow through the wavetube.

In general, it is an object of the present invention to provide a fuelsupply system, carburetor for use therein and method which makespossible a wide range of operation.

Another object of the invention is to provide a system, carburetor andmethod of the above character in which marked pressure drops areeliminated.

Another object of the invention is to provide a system, carburetor andmethod of the above character in which emission of unburned hydrocarbonsand carbon monoxide is substantially reduced.

Another object of the invention is to provide a system, carburetor andmethod of the above character in which the air-to-fuel ratios can bevaried through wide ranges if desired.

Another object of the invention is to provide a system, carburetor andmethod of the above character which are applicable to internalcombustion engines whether reciprocating or rotary and whether twostrokeor four-stroke cycle.

Another object of the invention is to provide a system, carburetor andmethod of the above character in which the correct amount of fuel andthe highest possible degree of atomization is provided.

Another object of the invention is to provide a system, carburetor andmethod of the above character which are applicable to multi-cylinderengines.

Another object of the invention is to provide a system, carburetor andmethod of the above character which are relatively simple.

Another object of the invention is to provide a system, carburetor andmethod of the above character which make possible improved throttleresponse.

Another object of the invention is to provide a system, carburetor andmethod of the above character which make possible the efficient use offuel.

Another object of the invention is to provide a system, carburetor andmethod which can be imple mented relatively inexpensively.

Another object of the invention is to provide a system, carburetor andmethod of the above character in which shock waves are used for causingintake of fuel and atomizing the same.

Additional objects and features of the invention will appear from thefollowing description in which the preferred embodiments are set forthin detail in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view ofthe carburetor utilized in the fuel supply system incorporating thepresent invention.

FIG. 2 is a top plan view looking along the line 22 of FIG. 1.

FIG. 3 is a side elevational view looking along the line 3-3 of FIG. 1.

FIG. 4 is a cross-sectional view taken along the line 4-4 of FIG. 3.

FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 1.

FIG. 6 is a cross-sectional view taken along the line 6-6 of FIG. 4.

FIG. 7 is a top plan view of the carburetor similar to FIG. 2 butshowing additional details.

FIG. 8 is a cross-sectional view taken along the line 88 of FIG. 7.

FIG. 9 is a schematic illustration of a fuel bowl with which air controlis utilized.

FIG. 10 is a schematic illustration showing a fuel supply systemincorporating the present invention utilizing air control.

FIG. 11 is a schematic illustration showing a fuel bowl with which pumpcontrol is utilized.

FIG. 12 is a schematic illustration of a fuel supply systemincorporating the present invention utilizing pump control.

FIG. 13 is a front elevational view partly in cross section of amulti-cylinder internal combustion engine of a four-stroke cycle havinga fuel supply system mounted thereon incorporating the presentinvention.

FIG. 14 is a cross-sectional view taken along the line 14-14 of FIG. 13.

FIG. 15 is a cross-sectional view showing an internal combustion engineof the two-stroke cycle and having a fuel supply system mounted thereonincorporating the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 through 8 there isshown a carburetor 21 for use in a fuel supply system incorporating thepresent invention. This carburetor 21 has the principal novelty in thesystem and consists of a body or housing 22 and a base 23 which can beformed of a suitable material such as an aluminum alloy sand casting. Ifdesired, die cast aluminum can be utilized for high volume production.Alignment pins 24 are provided either in the body or the base 23 and areprovided for aligning the base 23 on the body 22. The base and the bodyare fastened together in a suitable manner such as by the use of Allenhead screws 26. They extend through the body 22 and are threaded intothe base 23 as shown.

The body 22 is provided with a cylindrical bore 28 which is of uniformor constant cross-sectional area. The bore 28 opens into a generallyplanar oval-shaped recess 29 (see FIG. which receives a throttle plateor a slide valve 31. The slide valve 31 is formed of a suitable materialsuch as a phenolic laminate, Nema grade LE. The slide valve 31 isprovided with a bore 32 which has substantially the same diameter as thebore 28 provided in the body or housing 22. The base 23 is also providedwith a bore 33 which is in axial alignment with the bore 28 and is ofsubstantially the same size as the bore 23. As can be seen from thedrawing, the slide valve 31 is adapted to be moved between athrottle-full open position in which the bore 32 is in axial alignmentor registration with the bores 28 and 33 and a throttleclosed positionin which the slide valve 31 occludes communication between bores 28 and33.

Means is provided for retaining the slide valve 31 in thethrottle-closed position and consists of a coil spring 36 which has oneend seated in a well 37 provided in the slide valve 31 and having theother end engaging the wall forming the recess 29 and encircling a tube38 mounted in the body (see FIG. 4). Means is provided for causingmovement of the slide valve 31 between the throttle-closed position andthe throttle-open position and consists of a cable 41 which extendsthrough the sleeve 38, through the coil spring 36 and is fastened into acounterbore 42 in the slide valve 31 by a screw 43.

A tube 45 ofa substantially constant or uniform cross section isprovided which has an outer flared end portion 460. As shown in FIG. 4,the tube 46 is secured within a bore 47 provided in the body 22. Asshown in the drawings, the tube 46 is cylindrical and has a flow passage48 extending therethrough which has a diameter which is substantiallyidentical to the diameter of the bore 28 in the body 22 and the bore 33provide what may be called a wave tube of a substantially constant oruniform cross-sectional area extending completely through the carburetorand which is sized as hereinafter described.

Means is provided which forms a fuel supply orifice in the vicinity ofthe interior of the wave tube between the ends of the wave tube. Thus asshown in FIG. 4, a fitting 51 is threaded into the body 22 and into thetube 46 as shown in FIG. 4. The fitting 51 is provided with a conicalinlet recess 52 which opens into a small centrally disposed orifice 53.The orifice 53 opens into a downstream passage or channel 54 in thefitting which opens into and is in communication with the passage 48 inthe tube 46. As can be seen from FIG. 4, the exterior end of the fitting51 and the outer end of the passage or channel 54 are generally flushwith the inner cylindrical surface defining the passage 48. The channel54 extends in a direction at right angles to the axis of the passage 48.Also, the downstream channel 54 is positioned ahead of the slide valve31 and is spaced from the inlet end of the tube 46.

The inlet recess 52 of the fitting 51 opens into the interior chamber 56of a fuel bowl 57. The bowl 57 is formed of a suitable material such asan aluminum sand casting. It is provided with a pair of ears 58 (seeFIG. 3) which are secured to the main body 22 by Allen head screws 59. Acap 61 closes the open end 62 of the bowl 57. The cap 61 is providedwith a small vent hole 63 for venting the interior of the chamber 56 tothe atmosphere. Means is provided for introducing a liquid fuel such asgasoline into the chamber 56 of the bowl 57 and includes a fill tube 66which is mounted in the side wall of the bore 57. The fill tube 66 hasan inner conically-shaped end which has a small inlet opening 67 formedtherein. A control tube 68 is mounted in the cap 61 and also has aninner tapered conical end which has a small opening 69 formed therein. Adrain tube 71 is mounted in the side wall of the bowl and has its inletend open to the interior of the bowl. The fill tube 66 is normallypositioned at a level which would be below the level of the fuel withinthe chamber 56. The control tube 68 is positioned in such a manner sothat the opening 69 is only a slight distance above the axis of the orifice 53 so that the fuel level is just slightly above the orifice. Thedrain tube 71 is normally positioned in such a manner so that it wouldbe above the normal liquid fuel level within the bowl 57.

The carburetor 21 is adapted to be mounted on an internal combustionengine 76 of a conventional type as shown in FIG. 3. As is well known tothose skilled in the art, such internal combustion engine is providedwith an engine block 77 having a piston (not shown) which reciprocatesor moves therein. The engine block 77 is provided with an inlet passage78 which is in controlled communication through an inlet valve 79 withthe combustion chamber provided above the piston. The carburetor 21 ismounted in a suitable manner such as by a pair of screws 81 which extendthrough the base 23 and are threaded into the engine block 77. As willbe noted from FIG. 8, the passage 78 has substantially the same size asthe wave tube for a purpose hereinafter described.

A schematic illustration of the fuel bowl 57 provided in the carburetor21 utilizing air control is shown in FIG. 9. A schematic illustration ofthe manner in which fuel is supplied to the bowl 57 is shown in FIG. 10.As shown in FIG. 10, the fuel is carried in a tank 86 formed of asuitable material such as steel or fiberglass. The tank 86 is thermallyinsulated in a suitable manner such as by a layer 87 of rigidpolyurethane foam which may be provided with an epoxy overcoat. The tank86 is provided with an air tight filler cap 88. Fuel 89 is provided inthe tank which flows through an outlet pipe 91 and through a shut-offvalve 92 through a pipe 93 to a hose 94 which is connected to the filltube 66. Fuel 89 flows into the chamber 56 from the fill tube 66 byforce of gravity until the opening 69 in the control tube 68 is occludedby the liquid fuel 89. The control tube 68 is connected by a hose 96which is connected to a tube 97 mounted on the tank 86 and which entersthe tank near the fill cap 86 and is in communication with the space 98in the upper portion of the tank as shown in H6. 10. i

As soon as the opening 69 in the control tube 68 is occluded, air can nolonger pass into the space 98 above the liquid fuel 89 so that within avery short time, a partial vacuum or a below atmospheric condition iscreated in the space 98 which prevents further flow of fuel from thetank 86. In the event there is overfilling of the chamber 56, the excessfuel will pass through the drain tube 7] after which it can be returnedto the tank 86 if so desired. Fuel 89 from the chamber 56 is meteredthrough the orifice 53 into the carburetor as hereinafter described.

As pointed out previously, the fuel flows into the bowl until the tip ofthe control tube is covered and a partial vacuum is generated in the airspace 98 above the fuel in the tank. The pressure difference betweenatmospheric and the air space in the tank is determined by the densityof the fuel in the tank times the acceleration of gravity times thedifference in height between the fuel level in the tank and the fuellevel in the bowl.

In connection with the fuel supply bowl, it is always important that thefuel level be at a level which is just slightly above the orifice 53 sothat fuel can be readily drawn into the orifice 53 when the shock wavepasses the orifice.

lt has been found that the fill and control orifices or openings 67 and69 should be approximately the same diameter when gasoline is beingutilized as a fuel. By establishing a relationship between the orificesizes and the surface area of fuel in the bowl, overshooting isprevented and maximum accuracy is provided with a predetermined fuelfeed rate requirement.

In providing the fitting 5], it has been found that it is desirable toprovide a conical entry for the inlet recess 52 and a length-to-diameterratio of approximately 0.7 for the orifice 53. The downstream channel orbore 54 preferably has an area which is approximately 10 times thecross-sectional area of the orifice 53.

ln mounting the careburetor on the engine, it is important that thecarburetor 21 be mounted in such a manner that the bowl with its fitting51 have the inlet orifice 53 of the fitting point in a forward directionor in the direction of movement of the vehicle in which the engine ismounted so that when the vehicle accelerates, a change in fuel levelwill be in a positive direction so that the orifice 53 will not bestarved of fuel.

A phenolic has been chosen for the slide valve because it has atemperature coefficient of expansion which is very similar to that ofaluminum alloy castings. In addition, since gasoline is a very poorlubricant, it is desirable to utilize a material for the slide valvewhich will not bind or stick in its movement in the carburetor.Therefore, preferably, the material should be nonmetallic.

Operation and use of the carburetor 21 with a fuel system of the typeherein described in conjunction with an internal combustion engine maynow be briefly described. Let it be assumed that the slide valve orthrottle plate 3| has been moved to a full open position orthrottle-open position so that the bore 32 provided therein is inalignment with the bores 33 and 28 whereby there is provided a wave tubeof substantially constant cross section extending from the inlet port 78of the internal combustion engine to which the carburetor is connectedto the atmosphere. As is well known to those skilled in the art, a shockwave is created by the combination of piston motion and sudden openingof the inlet valve 79. It has been found that the specific form of theinlet valve or the specific form of the cylinder has relatively littleeffect on the generation of the shock wave other than to slightly modifythe shape of the same. This shock wave is created by these two featuresof engine operation and is propagated down the intake passage 78 anddown the wave tube formed by the bore 33,, the bore 32, the bore 28 andthe passage 48 at the velocity of sound in air. The shock wave pressuredoes not differ markedly in pressure from atmospheric pressure to whichthe outlet end of the tube 46 is exposed. As hereinafter pointed out,the design parameters for the wave tube are chosen such that the shockwave pressure will not be in excess of 10% from that of atmosphericpressure.

During the time that the shock wave is being propagated, it should beappreciated that there is a relatively steady state airflow entering thewave tube from the inlet end of the wave tube which passes thrugh thewave tube as a moving column of air of generally uniform cross sectionand then passes into the inlet passage 78 past the inlet valve 79 intothe combustion chamber above the piston. During the time this isoccurring, the shock wave is being propagated outwardly from the tubethrough the column of air and as it passes the flow channel 54, it willpump fuel through the orifice 53 and will atomize the same into veryfine droplets so that it will be carried by the moving column of airinto the combustion chamber above the piston. The amount of fuel whichis atomized is dependent upon the time that the shock wave is effectiveand is directly determined by the length of the wave tube. The outgoingshock wave is of the correct sign of pressure to meter fuel from theorifice 53 and to atomize the same so that it can be carried to theengine by the steady state air stream. The outgoing shock wavepropagates outwardly until it reaches the end of the tube at which timea reflected wave is created which is of the opposite sign of pressurewhich propagates as an ingoing wave. Since this shock wave has apressure of the incorrect sign, no fuel will be metered from the orifice53 when this wave passes the orifice 53. This ingoing wave will not haveany effect on the fuel which has already been metered out of the orifice53 by the outgoing wave because the atomized fuel has already beencarried inwardly toward the engine combustion chamber. This will alwaysbe true because the outgoing and ingoing waves are opposite in sign andwill be delayed in time with respect to each other.

The length of time required for the incoming wave to reach the flowchannel 54 is determined by the length of the tube and the speed ofsound in air. As is hereinafter explained, it has been found desirableto select the length of the wave tube such that the round trip time forsound to travel in the wave tube in air corresponds to approximately 40of crankshaft travel at the maximum useful engine speed.

In considering the design of the wave tube, it should be considered thatthe degree of atomization of a liquid fuel in air is dependent upon therelative velocity between the liquid fuel and the air. As this velocitybecomes an appreciable fraction of the velocity of sound, both the meandrop size and the variation in drop size decrease to small values,dependent upon the surface tension of the fuel. For this reason, it isdesirable to atomize fuel at a sonic velocity if possible to therebyinsure the maximum degree of atomization of the liquid fuel.

in considering the wave tube utilized in the present carburetor as onehaving a constrant or uniform crosssectional area and having a steadyvolume air flow rate q, certain determinations can be made. Neglectingfriction, the steady-state pressure p qd/ZA where d is the density ofair in the tube, and A is the cross-sectional area of the tube. If it isshown that there is a demand for this volume air flow rate through thetube immediately after the sudden opening of the intake valve, a shockwave will be propagated down the intake tube generating an acousticpressure where c is the velocity of propagation, which for a weak shockwave is equal to the velocity of sound in air. The ratio of acousticpressure to steady state pressure is ZcA/q and since q/A v, where v isthe steady state air velocity, then p'/p= 2c/v. Thus, it will be seen atlow steady state air velocities, the steady state pressure is negligiblecompared to the acoustic pressure. This acoustic pressure will persistuntil the shock wave, traveling at the speed of sound, makes the roundtrip from the intake valve to the open end of the wave tube and backagain.

The length and diameter of the intake wave tube determine the range ofengine operation over which sonic atomization, fuel metering linearityand minimum steady state pressure loss may be achieved. For example, ifthe maximum pressure loss at peak engine speed is chosen not to exceed5% and the maximum metering non-linearity is chosen not to exceed 5%.,the optimum diameter of the intake wave tube is determined by D=2.58 X xV VNe (cm),

where V is the displacement volume of the cylinder in cm, N is themaximum engine speed in rpm, and e is the fractional volumetricefficiency at maximum engine speed. The length of the intake wave tubeis determined by L= l.l5 X lo /N (cm).

Increasing the diameter of the intake wave tube above this valueincreases the minimum engine speed at which sufficient atomizationenergy is avaiable, since p is proportional to the square of the ratioof engine speed to tube area, while decreasing the diameter of theintake tube below this value increases the steady state pressure loss atpeak engine speed approximately inversely as the 4th power of the tubediameter. The length of the intake tube is less critical. Decreasing thelength of the tube raises the minimum engine speed only inversely as thelength, while increasing the length of the wave tube introduces somemetering nonlinearity and friction loss.

The location of the slide valve or sliding throttle plate 31 relative toits longitudial position with respect to the axis of the wave tube isselected so that at part throttle openings, an increase in air/fuelratio occurs consistent with the nominal requirements of the engineunder part load conditions. This results in better fuel economy andlower carbon monoxide and unburned hydrocarbon emissions. This occursbecause the effective length of the intake tube, which directlydetermines the metering pressure from a given fuel jet size, is reduced.Optimum placement of the slide valve depends on the parameters of theengine on which the carburetor is mounted and the desired operatingconditions.

if desired, the physical spacing and the angular orientation of the axisof the fuel jet with respect to the axis of the throttle plate may bevaried to tailor the partthrottle air/fuel ratio because the steadystate air flow, which carries atomized fuel droplets into the combustionchamber, has a much smaller angle of convergence approaching thethrottle plate than the shock wave. Therefore, the air/fuel ratio may beincreased at low throttle settings by hiding the fuel jet behind thethrottle plate by rotation of the jet axis in a plane parallel to thethrottle plate and/or increasing the distance between the jet axis andthe throttle plate. In this connection, it should be noted that theincrease in air/fuel ratio is more strongly controlled by a function ofrotation than the distance at very low throttle settings.

it should be appreciated that full throttle or open throttle is when thepassage or bore 32 in the slide valve is in complete registration withthe bores or passages 28 and 33 and that this throttle opening can begradually decreased by releasing the cable 41 and permitting the spring36 to move the slide valve or throttle plate 31 to the right as viewedin FIG. 4 to progressively close off the wave tube.

The flared outer end of the wave tube minimizes entrance losses.

lt should be noted that the fitting 51 is placed in the wall of the wavetube 46 because the axial position of the orifice 53, for the purposesof metering fuel into the wave passages, is relatively immaterial. Thisis true because the shock wave, after it passes through the slide valveor throttle plate, expands almost immediately so that it willeffectively atomize any fuel which it draws into the wave tube.

in connection with the design of the carburetor and the fuel systemincorporated in the present invention, it has been found desirable toterminate the returning or incoming shock wave so that no further shockwaves are produced. For this purpose a viscous acoustical resistance hasbeen provided in the form of a slot 101 (see FIGS. 2 and 4) formed inthe base 23. The slot 101 extends the width of the base 23 and is opento the atmosphere on both sides. The slot has a width which is onlyslightly greater than the interior diameter of the wave tube. The slot10! serves as a terminating slot and in effect absorbs the incomingshock wave so that there are no further reflections from the shock tube.Thus, each shock wave can only make one round trip through the wavetube. Further reflections of the shock wave are eliminated to preventsuch reflections from causing perturbations in the metering linearityover the operating range of the internal combustion engine on which thecarburetor is mounted. As can be seen, the slot 101 is positionedimmediately adjacent to and opens into the bore 33.

It is possible under certain conditions of engine operations where avery high air/fuel ratio, that is, a very lean mixture, is desired, asunder part throttle conditions, that supplemental means he provided toincrease the air/fuel ratio. Because of the form of the throttle plateor slide valve, it is expedient to utilize the movement ofthis throttleplate to admit supplemental acoustical resistance which is effectivelyin parallel with the wave tube such that the acoustical impedancelooking into the tube becomes much lower. This will lower the shock wavepressure, thus metering less fuel for a given value of steady stateairflow thrugh the wave tube and thereby producing the desired increasein air/fuel ratio. For this purpose a thin slot 102 is milled into thebody 22 and is open to the recess 29. A hole 103 is formed in the body22 and is in communication with the slot 102 and is open to theatmosphere. The slot 102 and the hole 103 serve to provide a variableacoustical impedance as the throttle valve is moved. Hole 103 servesmerely to expose slot 102 to the atmosphere. By placing this slot 102close to the longitudinal axis of the slide, a monotonically increasingair/fuel ratio is ob tained with a decrease in throttle opening. Byproper placement of slot 102, great latitude can be obtained in mixturecompensation. It should be appreciated, however, that the depth of slot102 should be relatively small to maintain the desired ratio ofacoustical resistance to inductive rcactance of slot 102. The acousticalresistance of the slot 102 varies as the 4th power of the depth of theslot 102 whereas the inductive rcactance varies directly as the depth ofthe slot. lt is preferable to maximize the ratio of the acousticalresistance relative to the inductive rcactance because it is theacoustical resistance which is most effective in modifying the shockwave pressure.

In operation of the carburetor 21 on an internal combustion engine, thecarburetor can be positioned in any desired position. Thus, for example,the wave tube can be positioned so that it is a side draft wave tube ora down draft wave tube. It is only important that the fuel supply bowland the orifice therein be positioned in such a manner that the level ofthe fuel in the fuel bowl barely covers the orifice.

Another embodiment of the fuel control system incorporating the presentinvention is shown in FlGS. 11 and 12, utilizing a pump control. Forthis purpose. a fuel supply bowl 111 similar to the bowl 57 can be provided. It is provided with an inlet or fill tube 66 as well as a draintube 71. The control tube 68 is omitted. The fitting 51 and the draintube 71 are positioned so that the lower-most point of the drain tube isflush with the upper portion of the orifice 53. in such a bowl, fuel issupplied by a pump to the fill tube 66 continuously and the excess fuelwhich is not utilized drains away through the drain tube 71. At alltimes the fuel 89 is maintained at a level which just covers the orifice53.

In FIG. 12, there is shown a fuel supply system utiliz ing a pluralityof fuel supply bowls 11] such as would be used in connection with aneight-cylinder internal combustion engine. The fuel 89 is supplied fromthe tank 113 through a pipe 114 to an engine-driven pump 116. The pump116 supplies fuel through a throttleaetuated regulator 117 to a line 118which is connected to the fill tube 65 of each of the fuel supply bowls111. A line 119 is connected to the drain tubes 71 and is connected intothe space 121 overlying the fuel in the tank 113 so that it can bereadily drained into the tank by gravity flow. Thus, fuel will becontinuously supplied to each of the fuel supply bowls 111 so that itcan be supplied to the wave tube of the carburetor associated therewith.

In FIGS. 13 and 14 there is shown how the present carburetor and fuelsupply system can be incorporated into an eight-cylinder internalcombustion engine having a 4-stroke cycle. Thus, as shown in FIGS. 13and 14, there has been provided an internal combustion engine 131 of aconventional type. Such an engine includes a block 132 provided withcylinders 133 having reciprocating or moving pistons 134 mountedtherein. The combustion chamber 136 is provided above the piston and isadapted to be placed in communication with an intake passage 137 throughan intake valve 138 operated by a cam 139. Similarly, the combustionchamber 136 is adapted to be placed in communication with an exhaustpassage 141 through an exhaust valve 142 operated by a cam 143.

A carburetor 146 incorporating the present invention is provided foreach of the cylinders of the internal combustion engine. As can be seen,the carburetors 146 are mounted upon the engine block. The carburetors146 are provided with wave tubes 148 of the type hereinbefore described.in addition, the carburetors are also provided with fuel supply bowls149 similar to those hereinbefore described. As can be seen from FIGS.13 and 14, the wave tubes of the carburetors are inclined upwardly at asuitable angle such that the wave tubes 148 are coaxial with the intakepassages 137. Means is provided on the engine 131 for filtering the airentering the carburetors 146 and consists of a box-like enclosure 151which is mounted on the engine and which is provided with a removablecover 152 to permit access to the carburetors 146. The housing or catsing 151 is provided with louvered openings 153 through which air passesinto the housing 151 and thence through filters 154 mounted on the sidesof the container as shown in FIG. 13. In this way, all air entering thecarburetors 146 will be filtered.

As can be seen from FIG. 14, the four carburetors provided on each sideof the enginer are formed from a common body casting 161 which extendssubstantially the entire length of the engine and a common base casting162 both of which are fastened together by the screws 147. The basecasting is secured to the block 132 by screws (FIG. 13). Similarly, acommon throttle plate is therefore provided with four holes or openings167, one of which is associated with each carburetor.

Means is provided for operating the throttle plate 166 and consists of alinkage mechanism 169. The linkage mechanism consists of a shaft 171which is rotatively mounted in L-shaped arms 172 and secured to thehousing 151. A plate 173 is secured to the shaft 171 and has a linkage174 connected thereto which extends downwardly through a slot 176 in thehousing 151. The linkage 174 is connected to a conventional acceleratormechanism such as that utilized in an automobile so that the shaft 171can be rotated by operation of the acceleration pedal. Two arms 176 areprovided on opposite ends of the shaft 171 and are connected. by balland pivot assemblies 177 to threaded shafts 178 which are connected toball and pivot assemblies 179 secured to the throttle plates 166. Thus,it can be seen that as the shaft 171 is rotated, the throttle plates 166will be moved simultaneously. Means is provided for returning thethrottle plates to positions in which the holes 167 are out ofregistration with the wave tubes of the carburetor and consists ofsprings 181 secured to posts 182 1 l secured to the body castings 161and posts 183 secured to the throttle plates 166.

The fuel supply system which is utilized in the embodiment of theinvention shown in FIGS. 13 and 14 is of the pump control type and fuelis supplied under pressure from the pump through line 191 to a regulator192. The regulator 192 supplies its output to a pipe 193 which isconnected by lateral extensions 194 through tubes 196 to the fillertubes of the fuel supply bowls 149. The operation of the regulator 192is controlled through the accelerator linkage as is shown in FIG. 14.The arm 173 is connected by a pivot and ball assembly 201 to a threadedrod 202 which is connected by a pivot and ball assembly 203 to an arm204 mounted on the regulator.

The drain tubes of the fuel supply bowls 149 are connected to tubes 206which are connected to two extensions 207 of a drain pipe 208. As can beseen from FlG. 13, the drain pipe 203 is at the level which issubstantially below the level of the drain pipes from the carburetors sothat in the event the engine is tilted during operation fuel from onecarburetor will not flow into the carburetor on the other side.

The operation of this embodiment of the invention is similar to thathereinbefore describedd with the principal difference being that thereare a plurality of carburetors and cylinders provided for the internalcombustion engine. From the concentration shown it can be seen that allof the carburetors will operate in unison with the cylinders to supplythe so-desired fuel/air mixture to the cylinders. All of the advantagesdescribed in the preceding embodiments are applicable to the presentembodiment. The shock wave is utilized for automization of the fuel.This fuel atomization is accomplished in a very efficient manner withouta marked pressure drop which gives increased performance and increasedrange of operation. The air/fuel ratio is carefully controlled so thatthere is a reduction of unburned hydrocarbons and carbon monoxide. Sincethe carburetor utilized is relatively simple, manufacturing andmaintenance costs are greatly reduced. While obtaining the maximumdegree of atomization and providing for efficient use of fuel, there isexcellent throttle response and a 60 z 1 range of efficient airflow ratehandling capability.

Still another embodiment of the invention is shown in P10. 15 whichshows the applicability of the invention to two-stroke cycle engines.Thus, as shown in FIG. 15, there is provided a two cycle engine 216which is provided with a cylinder 217 which has a reciprocating piston218 therein. The engine block 219 is provided with a transfer passage221 which is controlled by the piston 218. The block is also providedwith an exhaust passage 222 also controlled by the piston. The pistondrives the crankshaft 223 which is rotatably mounted on the block. Thecrankshaft 223 drives a rotary valve 224 which is provided with a boreor passage 226 which is adapted to be moved into registration with anintake port 227 provided in the block. This bore 227 is in registrationwith the wave tube of a carburetor 231 incorporating the presentinvention. As shown in FIG. 15, the carburetor 231 is mounted in a sidedraft fashion and utilizes an air control tube 232 for controlling theflow of fuel into the fuel bowl. The carburetor 231 operates in themanner hereinbefore described as with the other embodiments of theinvention. A shock wave is formed within the two cycle engine similar tothe four cycle engine and is propagated down the wave tube to atomizethe fuel as hereinbefore described. A throttle plate 234 is provided forcontrolling the fuel supplied to the engine to thereby regulate thespeed of operation of the engine.

It is apparent from the foregoing that there has been provided a fuelsupply system and carburetor incorporated in the same which utilizes aunique method for atomizing fuel and introducing the same into thecombustion chamber of internal combustion engines. An airflow withoutsignificant pressure drops is provided for movng the atomized fuel intothe combustion chamher. The emission of unburned hydrocarbons and carbonmonoxide is substantially reduced. Very accurate control of air/fuelratio can be obtained.

1 claim:

1. A fuel supply system for an internal combustion engine having atleast one combustion chamber which is adapted to be placed incommunication with an intake opening during each intake event,comprising wall means forming a wave tube having a substantiallyunimpeded flow passage with one end open to the atmosphere and with theother end adapted to be placed in communication with the intake openingof the internal combustion engine, means forming an orifice disposed inthe wall means forming the wave tube and opening into the flow passageof the wave tube, means for supplying fuel to the orifice so that thefuel has a level which will reach the orifice but will not flow throughthe orifice solely because of the level of the fuel with respect to theorifice, and throttle valve means disposed in the wave tube between theregion in which the fuel is introduced into the wave tube and the intakeopening, said throttle valve means being formed so that a shock wavefrom the engine can be propagated down the wave tube to cause fuel to bedrawn into the wave tube through the orifice substantially solely duringpropagation of the pressure shock wave along the wave tube and toatomize the fuel so that the atomized fuel can be carried into thecombustion chamber by the incoming air stream flowing in the wave tube,the pressure effect of said wave serving as substantially the sole meansfor metering fuel from the orifice, said wall means forming a wave tubeincluding a body, said body being formed with shock wave terminatingmeans for preventing a shock wave from traveling substantially more thanone round trip in the flow passage in the wave tube for each intakeevent.

2. A system as in claim 1 wherein said means for supplying fuel includesa fuel supply bowl, means for supplying liquid fuel to the fuel bowl,control means for preventing liquid fuel from being introduced into thefuel bowl to a level which is significantly above the orifice and adrain tube connected to the fuel bowl for draining off excess liquidfuel from the fuel bowl.

3. A system as in claim 2 wherein said drain tube is connected to thefuel bowl at a position which is above the orifice.

4. A system as in claim 2 wherein said control means for preventing fuelfrom being introduced into the fuel bowl to a level which issignificantly above the orifice includes said drain tube.

5. A system as in claim 1 wherein said body has an elongate recessformed therein with a bore opening into the recess and wherein saidthrottle valve is in the form of a throttle plate slidably mounted insaid recess in said body, for movement between throttle open andthrottle closed positions, saidthrottle plate having an opening thereinadapted to be moved into registration with said bore in said body sothat it is in alignment with and forms a part of the wave tube when thethrottle plate is in the throttle open position and is out ofregistration with said bore in said body in the throttle closedposition.

6. A system as in claim together with yieldable means for urging saidthrottle plate into a position so that the bore in said body is occludedby said throttle plate.

7. A system as in claim 6 together with means for moving said throttleplate so that the opening in said throttle plate is in registration withsaid bore in said body against the force of said yieldable means.

8. A system as in claim 1 wherein said terminating means is in the formof at least one opening located in the body and establishescommunication between the atmosphere and the flow passage.

9. A system as in claim 5 together with supplemental air bleed meansformed in the body in communication with the flow passage under thecontrol of the throttle valve.

10. A system as in claim 9 wherein said supplemental air bleed means isprovided by a slot in the body open to the recess in the body and a holein the body in communication with the slot and being open to theatmosphere.

11. In a carburetor, a body having a bore therein, said body beingformed with a recess and a throttle plate slidably mounted in said body,said throttle plate having a hole therein adapted to be moved into andout of registration with said bore in said body by movement of thethrottle plate, said bore in said body and said hole in said throttleplate being adapted to form a substantially unimpeded flow passage, saidbody being formed with terminating means extending substantiallytransversely to the major axis of the flow passage and establishingcommunication between the bore in said body and the atmosphere forpreventing a shock wave in the flow passage from traveling substantiallymore than one round trip in the flow passage in the wave tube for eachintake event.

12. A carburetor as in claim 11 wherein said terminating means isdownstream the throttle plate.

13. A carburetor as in claim 11 together with means for yieldably urgingsaid throttle plate into a position in which said throttle plateoccludes said bore in said body.

14. A carburetor as in claim 13 together with means for moving saidthrottle plate into a position in which said hole is in alignment withsaid bore against the force of said yieldable means.

I5. A carburetor as in claim 11 together with means forming an orificein the body for admitting liquid fuel into said bore in said body.

16. A carburetor as in claim 15 together with a fuel bowl having achamber in communication with said means forming the orifice.

17. A carburetor as in claim 16 together with means for controlling thelevel of the liquid fuel in said chamber so that it is generally at thesame level as the orifice.

18. In a fuel supply system for an internal combustion engine of a typehaving a plurality of combustion chambers and having intake openingsadapted to be placed into communication with the combustion chambersduring intake events, the system comprising separate carburetor meansfor each of said intake openings, each of said carburetor meansincluding means forming a wave tube having a flow passage therein withone end open to the atmosphere and the other end in communication withan intake opening, means forming an orifice disposed in the wave tubefor supplying fuel to the interior of the wave tube, throttle valvemeans disposed in the wave tube between the region in which the fuel isintroduced and the intake opening, means for supplying liquid fuel tothe orifice at a level so that fuel will not flow through the orificesolely under the force of gravity and terminating means in the meansforming a wave tube for preventing a shock wave in the flow passage fromtraveling substantially more than one round trip in the flow passage foreach intake event.

19. A system as in claim 18, together with air cleaner means forfiltering the air prior to the time it is supplied to the wave tubes.

20. A system as in claim 18 wherein as a part of said throttle valvemeans certain of said carburetors are provided with a common throttleplate, said throttle plate having an opening therein for each of saidcertain carburetors.

21. In a method for introducing a fuel and air mixture into thecombustion chamber of an internal combustion engine, in which shockwaves are formed and in which a column of air flows into the combustionchamber during each intake event, providing a supply of liquid fueladjacent the column of air propagating a shock wave created in theengine outwardly through the column of air to cause fuel to be drawninto the column of air and to be atomized so that the atomized fuel cantravel with the column of air, providing a reflected shock wave whichtravels inwardly through the column of air, and substantiallyattentuating the reflected shock wave so that there is substantiallyonly one round trip travel of the shock wave from and back to the engineduring each intake event.

22. A method as in claim 21 together with the step of confining themoving column of air in a wave tube having a substantially unimpededflow passage.

23. A method as in claim 22 together with the step of controlling thetime delay between the reflected shock wave and the outgoing propagatedshock wave by controlling the length of the wave tube.

24. A method as in claim 22 together with the step of controlling thepressure amplitude of the outgoing and reflected shock waves bycontrolling the crosssectional area of the wave tube.

25. A system as in claim 1 wherein said means for maintaining the levelof liquid fuel with respect to said orifice comprises a fuel bowl havingfuel therein at a predetermined level with an air space above the fuel,a sealed fuel supply vessel located at a level above said fuel bowl,means forming a fuel feed passage connecting said fuel bowl and saidfuel supply vessel, means forming a control passage between the airspace above the fuel in said fuel supply vessel and down to thepredetermined level in the fuel bowl, and means forming a vent passagein the fuel bowl between the air space above the fuel in said fuel bowland the atmosphere.

26. A system as in claim 1 wherein said means for maintaining the levelof liquid fuel with respect to said orifice comprises a fuel bowl havingfuel therein at a predetermined level with an air space above the fuel,a fuel supply vessel located at a level below said fuel bowl, meansforming a fuel feed passage between said fuel bowl and said fuel supplyvessel, fuel pump means connected in said means forming a fuel passagefor supplying fuel from said vessel to said bowl, means forming a fueldrain passage connected between said fuel bowl and said fuel supplyvessel, said means forming the drain passage being positioned in thebowl so that a predetermined fuel level is maintained in the bowl, andmeans in the fuel bowl forming a vent passage between the air spaceabove the fuel in said fuel bowl and the atmosphere.

27. A system as in claim 26 together with a fuel flow regulatorconnected into said means forming said fuel feed passage and which isresponsive to engine fuel demand whereby said regulator prevents excessfuel recirculation.

28. A fuel supply system for an internal combustion engine having atleast one combustion chamber which is adapted to be placed incommunication with an intake opening during each intake event,comprising wall means forming a wave tube having a flow passage for amedium therein with one end open to the atmosphere and with the otherend adapted to be placed in communication with the intake opening of theinternal combustion engine, means forming an orifice disposed in thewall means forming the wave tube and opening into the flow passagetherein, said flow passage being formed so that the maximum pressureeffect at the orifice due to a shock wave generated by the engine insaid medium in the flow passage is substantially greater than themaximum pressure effect at the orifice due to the velocity of saidmedium in the flow passage. said wall means forming a wave tubeincluding a body, said body being formed with shock wave terminatingmeans for preventing a shock wave from traveling substantially more thanone round trip along the flow passage in the wave tube for each intakeevent, means for supplying fuel to the orifice so that the fuel will beintroduced into the flow passage in the wave tube through the orificesubstantially only in response to said pressure effects at the orifice,and throttle valve means disposed in the wave tube between the region inwhich the fuel is introduced into the flow passage in the wave tube andthe intake opening of the internal combustion engine.

29. In a method for introducing a fuel and air mixture into a combustionchamber of an internal combustion engine, in which a shock wave isgenerated during an intake event in a medium confined by wall meansdefining an intake passage, the improvement of substantially terminatingthe progress of the shock wave after one round trip travel from and backto the engine of the shock wave in said medium for each intake event.

30. A method as in claim 29 together with the step of introducing fuelinto said medium substantially solely in a region adjacent the wallmeans defining an intake passage.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION F'ATENT NO. DATEDJuly 8, 1975 1NVENTOR(S) I William H. Beekhuis, Jr.

it as certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 15 Cancel "ranges" and substitute -rangeline 17 Cancel"gy" and substitute --by- Column 3, line 28 Cancel "23" and substitute--28- Column 4, line 36 Cancel "3" and substitute --8-- Column 6, line 9Cancel the extra comma after "33" Column 7, line 4 Cancel "constrant"and substitute -constant-- line 41 Cancel "l0 and substitute --10 line64 Cancel "lofigitudial" and substitute -longitudinal-- Column ll,linel9 Cancel "203" and substitute 208- line 25 Cancel "describedd" andsubstitute -described-- line 28 Cancel "concentration" and substituteconstructionlines 33-34 Cancel "automization" and substitute-atomization- Column l2,line l2 Cancel "movng" and substitute-movingfourth D3) 0f November 1975 [SEAL] Arrest:

C. MARSHALL DANN (nmmr'm'uner of Pa mm and Trademark:

1. A fuel supply system for an internal combustion engine having atleast one combustion chamber which is adapted to be placed incommunication with an intake opening during each intake event,comprising wall means forming a wave tube having a substantiallyunimpeded flow passage with one end open to the atmosphere and with theother end adapted to be placed in communication with the intake openingof the internal combustion engine, means forming an orifice disposed inthe wall means forming the wave tube and opening into the flow passageof the wave tube, means for supplying fuel to the orifice so that thefuel has a level which will reach the orifice but will not flow throughthe orifice solely because of the level of the fuel with respect to theorifice, and throttle valve means disposed in the wave tube between theregion in which the fuel is introduced into the wave tube and the intakeopening, said throttle valve means being formed so that a shock wavefrom the engine can be propagated down the wave tube to cause fuel to bedrawn into the wave tube through the orifice substantially solely duringpropagation of the pressure shock wave along the wave tube and toatomize the fuel so that the atomized fuel can be carried into thecombustion chamber by the incoming air stream flowing in the wave tube,the pressure effect of said wave serving as substantially the sole meansfor metering fuel from the orifice, said wall means forming a wave tubeincluding a body, said body being formed with shock wave terminatingmeans for preventing a shock wave from traveling substantially more thanone round trip in the flow passage in the wave tube for each intakeevent.
 2. A system as in claim 1 wherein said means for supplying fuelincludes a fuel supply bowl, means for supplying liquid fuel to the fuelbowl, control means for preventing liquid fuel from being introducedinto the fuel bowl to a level which is significantly above the orificeand a drain tube connected to the fuel bowl for draining off excessliquid fuel from the fuel bowl.
 3. A system as in claim 2 wherein saiddrain tube is connected to the fuel bowl at a position which is abovethe orifice.
 4. A system as in claim 2 wherein said control means forpreventing fuel from being introduced into the fuel bowl to a levelwhich is significantly above the orifice includes said drain tube.
 5. Asystem as in claim 1 wherein said body has an elongate recess formedtherein with a bore opening into the recess and wherein said throttlevalve is in the form of a throttle plate slidably mounted in said recessin said body, for movement between throttle open and throttle closedpositions, said throttle plate having an opening therein adapted to bemoved into registration with said bore in said body so that it is inalignment with and forms a part of the wave tube when the throttle plateis in the throttle open position and is out of registration with saidbore in said body in the throttle closed position.
 6. A system as inclaim 5 together with yieldable means for urging said throttle plateinto a position so that the bore in said body is occluded by saidthrottle plate.
 7. A system as in claim 6 together with means for movingsaid throttle plate so that the opening in said throttle plate is inregistration with said bore in said body against the force of saidyieldable means.
 8. A system as in claim 1 wherein said terminatingmeans is in the form of at least one opening located in the body andestablishes communication between the atmosphere and the flow passage.9. A system as in claim 5 together with supplemental air bleed meansformed in the body in communication with the flow passage under thecontrol of the throttle valve.
 10. A system as in claim 9 wherein saidsupplemental air bleed means is prOvided by a slot in the body open tothe recess in the body and a hole in the body in communication with theslot and being open to the atmosphere.
 11. In a carburetor, a bodyhaving a bore therein, said body being formed with a recess and athrottle plate slidably mounted in said body, said throttle plate havinga hole therein adapted to be moved into and out of registration withsaid bore in said body by movement of the throttle plate, said bore insaid body and said hole in said throttle plate being adapted to form asubstantially unimpeded flow passage, said body being formed withterminating means extending substantially transversely to the major axisof the flow passage and establishing communication between the bore insaid body and the atmosphere for preventing a shock wave in the flowpassage from traveling substantially more than one round trip in theflow passage in the wave tube for each intake event.
 12. A carburetor asin claim 11 wherein said terminating means is downstream the throttleplate.
 13. A carburetor as in claim 11 together with means for yieldablyurging said throttle plate into a position in which said throttle plateoccludes said bore in said body.
 14. A carburetor as in claim 13together with means for moving said throttle plate into a position inwhich said hole is in alignment with said bore against the force of saidyieldable means.
 15. A carburetor as in claim 11 together with meansforming an orifice in the body for admitting liquid fuel into said borein said body.
 16. A carburetor as in claim 15 together with a fuel bowlhaving a chamber in communication with said means forming the orifice.17. A carburetor as in claim 16 together with means for controlling thelevel of the liquid fuel in said chamber so that it is generally at thesame level as the orifice.
 18. In a fuel supply system for an internalcombustion engine of a type having a plurality of combustion chambersand having intake openings adapted to be placed into communication withthe combustion chambers during intake events, the system comprisingseparate carburetor means for each of said intake openings, each of saidcarburetor means including means forming a wave tube having a flowpassage therein with one end open to the atmosphere and the other end incommunication with an intake opening, means forming an orifice disposedin the wave tube for supplying fuel to the interior of the wave tube,throttle valve means disposed in the wave tube between the region inwhich the fuel is introduced and the intake opening, means for supplyingliquid fuel to the orifice at a level so that fuel will not flow throughthe orifice solely under the force of gravity and terminating means inthe means forming a wave tube for preventing a shock wave in the flowpassage from traveling substantially more than one round trip in theflow passage for each intake event.
 19. A system as in claim 18,together with air cleaner means for filtering the air prior to the timeit is supplied to the wave tubes.
 20. A system as in claim 18 wherein asa part of said throttle valve means certain of said carburetors areprovided with a common throttle plate, said throttle plate having anopening therein for each of said certain carburetors.
 21. In a methodfor introducing a fuel and air mixture into the combustion chamber of aninternal combustion engine, in which shock waves are formed and in whicha column of air flows into the combustion chamber during each intakeevent, providing a supply of liquid fuel adjacent the column of airpropagating a shock wave created in the engine outwardly through thecolumn of air to cause fuel to be drawn into the column of air and to beatomized so that the atomized fuel can travel with the column of air,providing a reflected shock wave which travels inwardly through thecolumn of air, and substantially attentuating the reflected shock waveso that there is substantially only one round trip travel of the shockwave from and back to the engine duRing each intake event.
 22. A methodas in claim 21 together with the step of confining the moving column ofair in a wave tube having a substantially unimpeded flow passage.
 23. Amethod as in claim 22 together with the step of controlling the timedelay between the reflected shock wave and the outgoing propagated shockwave by controlling the length of the wave tube.
 24. A method as inclaim 22 together with the step of controlling the pressure amplitude ofthe outgoing and reflected shock waves by controlling thecross-sectional area of the wave tube.
 25. A system as in claim 1wherein said means for maintaining the level of liquid fuel with respectto said orifice comprises a fuel bowl having fuel therein at apredetermined level with an air space above the fuel, a sealed fuelsupply vessel located at a level above said fuel bowl, means forming afuel feed passage connecting said fuel bowl and said fuel supply vessel,means forming a control passage between the air space above the fuel insaid fuel supply vessel and down to the predetermined level in the fuelbowl, and means forming a vent passage in the fuel bowl between the airspace above the fuel in said fuel bowl and the atmosphere.
 26. A systemas in claim 1 wherein said means for maintaining the level of liquidfuel with respect to said orifice comprises a fuel bowl having fueltherein at a predetermined level with an air space above the fuel, afuel supply vessel located at a level below said fuel bowl, meansforming a fuel feed passage between said fuel bowl and said fuel supplyvessel, fuel pump means connected in said means forming a fuel passagefor supplying fuel from said vessel to said bowl, means forming a fueldrain passage connected between said fuel bowl and said fuel supplyvessel, said means forming the drain passage being positioned in thebowl so that a predetermined fuel level is maintained in the bowl, andmeans in the fuel bowl forming a vent passage between the air spaceabove the fuel in said fuel bowl and the atmosphere.
 27. A system as inclaim 26 together with a fuel flow regulator connected into said meansforming said fuel feed passage and which is responsive to engine fueldemand whereby said regulator prevents excess fuel recirculation.
 28. Afuel supply system for an internal combustion engine having at least onecombustion chamber which is adapted to be placed in communication withan intake opening during each intake event, comprising wall meansforming a wave tube having a flow passage for a medium therein with oneend open to the atmosphere and with the other end adapted to be placedin communication with the intake opening of the internal combustionengine, means forming an orifice disposed in the wall means forming thewave tube and opening into the flow passage therein, said flow passagebeing formed so that the maximum pressure effect at the orifice due to ashock wave generated by the engine in said medium in the flow passage issubstantially greater than the maximum pressure effect at the orificedue to the velocity of said medium in the flow passage, said wall meansforming a wave tube including a body, said body being formed with shockwave terminating means for preventing a shock wave from travelingsubstantially more than one round trip along the flow passage in thewave tube for each intake event, means for supplying fuel to the orificeso that the fuel will be introduced into the flow passage in the wavetube through the orifice substantially only in response to said pressureeffects at the orifice, and throttle valve means disposed in the wavetube between the region in which the fuel is introduced into the flowpassage in the wave tube and the intake opening of the internalcombustion engine.
 29. In a method for introducing a fuel and airmixture into a combustion chamber of an internal combustion engine, inwhich a shock wave is generated during an intake event in a mediumconfined by wall means defining an intake passage, the improvement ofsUbstantially terminating the progress of the shock wave after one roundtrip travel from and back to the engine of the shock wave in said mediumfor each intake event.
 30. A method as in claim 29 together with thestep of introducing fuel into said medium substantially solely in aregion adjacent the wall means defining an intake passage.